How Does paper bag manufacturing Work?

Imagine a technology that could totally revolutionise packaging and the delivery of goods. That could protect and enclose and which could also feature branding and other information? Well, paper bags did just that when they emerged in the mid-late s in the US.

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But how are paper bags made, what are paper bags made from and what can paper bags be used for? In our guide, we take a look at the ingenuity and simplicity behind these useful everyday packing staples. And show you how they can be used for everything from storing your bits and bobs, to giving gifts the wow factor.

Who invented the paper bag?

While the inventor of the paper bag is lost to obscurity, the invention of the bag&#;s square bottomed design is widely accredited to one Luther Childs Crowell of Wellfleet in Massachusetts.

When was the paper bag invented? While Crowell&#;s flat-bottomed bag appeared in the s, one Francis Wolle, a US schoolteacher, invented the first machine to mass-produce these bags as early as the s. Wolle and his brother patented the machine and founded the Union Paper Bag Company, which leads us nicely to how paper bags are made.

How are paper bags manufactured?

Paper bags are manufactured from paper pulp, which is pressed into flat sheets or rolls of paper. These rolls of paper are cut to size, that means twice the required height of the finished bag. These cut sheets are then folded over and the two parallel open sides glued together. This can either be by pressing the glues sides together or heating and pressing.

This makes a simple flat bag made from paper.

To make a more complex flat-bottom design, a similar process is followed. Only, there are more complex folds at the bottom of the bag so that the finished bag is square or oblong with an open top.

For bags with handles, separate paper handles are then fixed using adhesive glue.

What are paper bags made out of

What are paper bags made of would, on the face of it, seem to be a silly question: paper. But there are many designs and styles, all made from different kinds of paper depending on what the bag is going to be used for.

Standard brown bags are made from Kraft paper, but it can be made from all kinds of paper and in any colour.

Kraft bags can also be made from laminated paper. This has a plastic coating on the inside to protect the bag from moisture from the goods contained in it or to keep moisture out.

Bags made from Kraft paper can also be designed in any colour and any weight of Kraft paper. These are typically made from 60gsm paper and come in a huge range of sizes.

More sturdy Kraft paper gift bags are made from 90gsm paper and can be coloured, or brown &#; or retro polka dot style.

As with all things paper, it can also be made from recycled paper and recycled Kraft paper. This offers a good, sturdy and environmentally friendly way to package goods, gifts and more. Typically, these are made from strong 110gsm recycled Kraft paper.

Why use paper bags?

Paper bags can be used for so many things. Bags made from paper are a cheap, easy and are a sustainable way to store and deliver all manner of things &#; so long as they aren&#;t wet, or really heavy.

How to measure a paper bag is simple: measure its height, width and depth (gusset) &#; multiply these together and you will get its volume.

How much can a paper bag hold depends on its size. These handy bags come in all sorts of sizes from small ones measuring 200x300x100mm right up to ones as big as sacks measuring 450x800x290mm.

How much weight can a paper bag hold depends again on its size and on the strength of the paper used. Small bags made of 70gsm Kraft paper have a breaking strain of 4kg, while the largest paper sacks made of 90gsm paper can take ten times that, having a breaking strain of 40kg.

In between lie the myriad sizes of bags available, each able to take a weight of 40kg or less. To see the full range of available sizes and their relative strengths, take a look at this chart.

For additional advice on paper packaging, our Packaging Experts are here to help you find the right solutions and arrange next day delivery. Simply call us on 542 44 28 or visit www.rajapack.co.uk.

Centuries before, using sacks made of jute, burlap, and jute were the primary methods of holding goods. Although they are sturdy, they are also time-consuming and expensive to produce back in the day. On the other hand, paper bags are portable and much more economical to process.

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Kraft paper bags became popular in the s when inventors developed the first technology to mass-produce them. Francis Wolle patented the first paper bag-making machine in . In , Wolle and his brother founded the Union Paper Bag Machine Company with a paper packaging plant that could create 1,000 feet of paper per minute.

Years later, Margaret Knight, a prolific inventor working for the Columbia Paper Bag Company, realized that Wolle&#;s envelope-like design or today&#;s pinch-bottom paper bag is not practical and efficient. So she created the square-bottomed packaging and built a machine that paved the way for the widespread commercialization of paper bags.

Since then, paper bags have been a market mainstay. But unlike before, technology has helped producers manufacture paper bags faster and with less waste and cost. Here are how commercial paper bags are processed today.

Preparation of Raw Material

Wood that a pulp mill receives can come in a variety of shapes and sizes. It could come in the form of round-wood bolts (short logs) with the bark still attached or as half-dollar-sized chips from a debarked round wood.

If manufacturers use round wood, a debarking process would be necessary. This is commonly done by tumbling the wood in huge steel drums with wash water. And if the pulping process requires chemical digestion, the debarked wood bolts are processed in a chipper. After that, the chips are sized, cleaned, and stored in preparation for further processing.

Fiber Separation

Here, the chips are stored in a big pressure cooker (digester) and applied with kraft pulping chemicals. The chips are digested with steam at precise temperatures in order to separate the fibers. This process also partially dissolves lignin and other extractives from the wood. These can weaken and discolor the paper if not removed.

Some digesters constantly run with a steady supply of chips (furnish), while others treat batches at a time. The cooked pulp is discharged into a pressure vessel after the digesting process. The steam and volatile materials are piped away, and the heated pulp is reintroduced into the chemical recovery cycle. Here, the pulp is screened, cleaned, and most of the water is removed in preparation for papermaking.

Bleaching Process

Because raw pulp still contains a significant amount of lignin and other discoloration, it must be bleached to produce white or light-colored papers, so they undergo bleaching. The order in which they are applied is determined by a variety of criteria. This includes the cost of bleaching chemicals, the type of pulp, and the state of the pulp.

This process also further dignifies the fibers through chlorination and oxidation. At the end of the process, the dissolved lignin is extracted from the surface of the fibers using sodium hydroxide.

Papermaking Procedure

The bleached and refined pulp then enters the paper mill and is mixed with water. This pulp solution goes through a series of rotating and stationary blades to make it more refined. The process gives the fibers clean-cut or &#;fibrillated&#; ends. Fibrillated fibers bind more tightly with other fibers, making the paper stronger.

Afterward, fillers like calcium carbonate and clay are added to make the paper opaquer and give it better density. To further improve the texture of the paper, manufacturers add dyes and optical brighteners. This final solution enters the paper machine, where the water is squeezed out, and the paper is dried and pressed.

Paper Sheering & Design Printing

The prepared sheets of paper are now stacked one on top of the other before being cut to the customer&#;s specifications. The shape and design of the paper bag are decided and implemented at this stage.

These papers go through a printing cylinder in a conventional or digital printing press. As it passes through the machine, the client-specified design is stamped into the paper. Typically, the process uses fast-drying solvent or water-based inks to attain quality print at high speed.

Eyelet Punching and Paper Creasing

After the sheering stage, certain details of the customer-specified paper bag handles will be applied to the paper. For example, if the paper bag is going to have rope handles, the material will undergo eyelet punching. The handles are also connected in the same process. If the bag has cut-out holes as handles, that will also be done at this stage.

After that, the paper is pleated to facilitate subsequent folding and sticking of the various sections of the bag. It guarantees that the bags are folded, stuck, and assembled in a consistent manner.

Hard Press

Clients may require their bags to be durable and strong at times. So sheets of paper are pasted together to create a double layer and make the paper bag thicker. After the adhesive is applied between sheets, a machine pushes them together for a clean and long-lasting bond.

Folding, Sticking, and Finishing

The manufacturing process has now reached its conclusion. At this stage, all of the bags&#; separately processed pieces, including the front, back, and side flaps, are assembled.

Usually, paper bag manufacturers use a tubing machine. The machine draws in the components, fold them together, and bond them with adhesive. Tuber speed generally runs at 150-250 feet per minute.

In certain procedures, depending on the design, the manufacturer adds another layer of paper for the bottom. This makes the lower part stronger so the paper bag would not easily tear when holding heavy objects.

After that, the application of the finishing touches, such as adding the rope handles, are also completed.

Bagitan Packaging &#; Your Source of Sustainable Paper Packaging

Bagitan Packaging manufactures professional paper bags, food packaging, and foil packaging for wholesale, retail, and redistribution. Our customizable packaging is sourced from 100% recyclable materials, making it suitable for brands that endeavor to deliver sustainable packaging to their customers. We handle bulk long-term supply and ship all over the world.

Contact us to discuss your requirements of paper bag manufacturing. Our experienced sales team can help you identify the options that best suit your needs.